If you like to hang out with friends, it might be due to the "love hormone" oxytocin, a new mouse study suggests.

Oxytocin promotes socialization by triggering pleasurable feelings when people get together, said Stanford University researchers.

"Our study reveals new insights about the brain circuitry behind social reward, the positive experience you often get when you run into an old friend or meet somebody you like," said study senior author Dr. Robert Malenka. He's associate chair of psychiatry and behavioral science at Stanford's School of Medicine.

"The reward circuitry is crucial to our survival because it rewards us for doing things that have, during our evolutionary history, tended to enhance our survival, our reproduction and the survival of our resulting offspring," he explained in a university news release.

For example, when you're hungry, food tastes great, he pointed out. "When you're thirsty, water is refreshing. Sex is great pretty much most of the time," he added.

Hanging out with friends has historically conferred a survival advantage, too, by decreasing the odds of getting eaten by predators, increasing chances of finding a mate and maybe helping to learn where food and water are, Malenka said.

He and his colleagues conducted a series of lab experiments that examined oxycontin's role in social behavior. Their findings were published Sept. 29 in the journal Science.

The findings could lead to new ways to help people who have difficulty socializing, including those with autism and schizophrenia, according to the researchers.